Integrated circuits or ICs are used in numerous applications, such as microprocessors, memories, application specific ICs (ASICs), graphics processors, and the list is an ever increasing list. As the IC (also commonly referred to as a “chip”) has evolved into a smaller and smaller package, with an ever increasing density of circuits, the task of designing chips or ICs that achieve a desired performance (e.g., faster processing speeds) has been challenged with an ever increasing issue concerning power consumption. Typically, the larger the power consumption for a chip, the higher the chip operating temperature. Higher operating temperatures may lead to a lower chip performance and even incorrect functioning of the chip. Managing power consumption for a chip may help in chip performance and correct operation of chip-based device. For example, managing the power consumption of ICs in a laptop may provide a longer battery life for battery operation of the laptop, while a reduced operating temperature may lead to less faults and greater operating longevity of the laptop.
Various approaches have been used to address the above issues. One approach has been to manage power consumption by controlling the clock frequency driving the circuitry of the chip. For example, Naffziger et. al. (U.S. Pat. No. 6,509,788) describes an embodiment in which an on-chip oscillator is utilized to provide the clock frequency for the chip's core circuitry. Such an oscillator can dynamically adjust the clock frequency to manage the chip's power consumption. As described, the oscillator is preferably operable to adjust its output frequency based on the voltage supplied to the oscillator to effectively manage the chip's power consumption. Design strategies attempting to utilize such dynamic variation of clock frequency and supply voltage based on computational loads are commonly referred to as dynamic voltage scaling (DVS). However, with all the DVS approaches, operating the circuitry of the chip at different clock frequencies may interfere with attaining the desired speed or throughput of the chip, and may be a limiting approach for very high-speed chips. Moreover, as described in Naffziger, an on-chip oscillator is required to generate the processor clock instead of the usual synchronous, externally controlled clock generator.
Another approach to managing power consumption of an IC device has been described by Gunther et. al. (U.S. Pat. No. 6,789,037). Gunther describes an integrated, on-chip thermal management system providing closed-loop temperature control of an IC device and methods of performing thermal management of an IC device. Through a temperature detection element, the temperature of the IC die may be detected and monitored. A power modulation element may reduce the power consumption of the IC device by limiting the speed at which the IC device executes instructions, by limiting the number of instructions executed, by directly lowering the power consumption of the IC device, or by a combination of these techniques. However, this approach may also be limiting for desired very high speed ICs.
Yet another approach to managing IC power consumption is provided in Georgiou et. al (U.S. Pat. No. 6,047,248). Georgiou describes a system and method using thermal feedback to cooperatively vary a voltage and frequency of a circuit to control heating while maintaining synchronization. Preferably, on-chip thermal sensors are used for feedback. Essentially, a voltage regulator and a clock selector are adapted to cooperatively vary the voltage and the frequency of the circuit to a predetermined voltage-frequency pair, responsive to a voltage/clock control signal that is enabled based on a decoded temperature signal and a predetermined temperature threshold. Again, however, changing the frequency of operation of the IC circuitry may have a negative impact on the desired higher speed operation of very high-speed chips.
In view of the above, and as a consequence of the long felt need for improvement in chip or IC power consumption efficiency, a method and system is needed for increasing the power efficiency of an IC through accurate management of the IC power consumption.